Despite everyone's insistence on how important Mysterion was to the town, he appeared to stop relatively small crimes. The only crimes we saw him stop were public disorderly conduct and graffitti by reporting them to the police. He also beats up Proffessor Chaos (Butters) and General Dissarray to stop them from blowing up a hospital (although fellow "hero" The Coon was really behind that plot) and his dialogue with Chaos indicates that he has probably stopped his "evil" plots before.